System and method for synchronizing external compression of a limb for increased blood

ABSTRACT

Embodiments relate to devices, systems and methods of assisting blood flow return to the heart from a limb. The device comprising a wearable garment and a compression apparatus embedded in the garment for applying an external compression to a limb of a user and at least one of a processor or a controller configured to control the compression apparatus to apply the external compression, according to a compression sequence, to a muscle of the limb of the user based on real-time measurements regarding a cardiac cycle having a diastolic phase and systolic phase of the user and real-time measurements of muscle activity. The compression sequence is synchronized to commence when both a local blood flow at the limb is in the diastolic phase and the muscle is in a non-contracted state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/142,931 filed Apr. 3, 2015, incorporated herein by reference as ifset forth in full below.

BACKGROUND

Embodiments relate to devices, systems and methods of assisting in bloodflow to the heart from a limb.

The vasculature in the body includes veins which have one-way valves toprevent a backflow of blood. In the lower extremities, extra work isrequired to move blood against gravity to the input side (right atrium)of the heart. The skeletal muscles assist the heart during perambulatorymotion by compressing veins in the lower extremities, aiding in emptyingthe venous circulation and therefore provide assistance in returningblood back to the heart against gravity. The skeletal muscles of thecalf or lower extremity muscle groups including, but not limited to, themajor muscle groups such as the soleus muscle and gastrocnemius muscle,have been identified as supporting this function. The lower extremitymuscle group's actions in facilitating the return of blood back to theheart are referred to as the skeletal muscle pump (human muscle pump) oras the second heart because these muscles provide assistive pumping ofvenous blood back to the heart from the periphery. The actions, namely,contraction of the muscles and resulting peristaltic blood flow in thelower extremities is generally known as the skeletal muscle pump, or thesecond heart effect. The skeletal muscle pump is essential formaintaining adequate venous and interstitial fluid flows in thedependent body.

During periods of inactivity or immobility, the continuous circulationof oxygenated blood throughout the body remains important forhomeostatic function. In specific instances of inactivity, the increasedcirculation of oxygenated blood can aid in future periods ofperambulatory motion and/or clinical treatment of a variety of diseases.This includes, but is not limited to, the removal of metabolic wasteproducts from localized tissue regions, amelioration of the symptoms ofmuscle fatigue, improved muscle performance in subsequent bouts ofexercise, and reducing the likelihood of thrombus formation. Forclinical treatments, increased circulation can prevent/reduce thelikelihood for thrombus formation, aid with wound healing, reduction ofedema, and reduce the stress on the cardiovascular system.

SUMMARY

Embodiments related to devices, systems and methods of assisting bloodflow to the heart from a limb. In an aspect, a device is providedcomprising a wearable garment; and a compression apparatus embedded inthe garment for applying an external compression according to acompression sequence to a muscle of a limb of a user based on real-timemeasurements regarding a cardiac cycle having a diastolic phase andsystolic phase of the user and real-time measurements of muscleactivity. The compression sequence is synchronized to commence when boththe local blood flow at the limb is in the diastolic phase and themuscle is in a non-contracted state.

An aspect of the embodiments include a system comprising a wearablegarment to be worn on a limb of a user; a cardiac cycle sensor toperform real-time measurements regarding a cardiac cycle having adiastolic phase and systolic phase of the user; a muscle activity sensorto perform real-time measurements of muscle contractions in the limb.The system includes a compression apparatus embedded in the garment forapplying an external compression to the limb of the user. A processor iscoupled to the compression apparatus to control the compressionapparatus to apply pressure, according to a compression sequence, to amuscle of the limb based on the real-time measurements of the cardiaccycle of the user and the real-time measurements of the muscle activity.The compression sequence is synchronized to commence when both the localblood flow at the limb is in the diastolic phase and the muscle is in anon-contracted state.

An aspect of the embodiments includes a method comprising: sensing, by acardiac cycle sensor, real-time measurements regarding a cardiac cyclehaving a diastolic phase and systolic phase of a user; sensing, by amuscle activity sensor, real-time measurements of muscle activity in alimb of the user; applying compression, by a compression apparatus, to amuscle in the limb of the user, and controlling the compression, by aprocessor coupled to the compression apparatus, according to acompression sequence, based on the real-time measurements of the cardiaccycle of the user and the real-time measurements of the musclecontractions wherein the compression sequence is synchronized tocommence when both the local blood flow at the limb is in the diastolicphase and the muscle is in a non-contracted state.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description briefly stated above will be rendered byreference to specific embodiments thereof that are illustrated in theappended drawings. Understanding that these drawings depict only typicalembodiments and are not therefore to be considered to be limiting of itsscope, the embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1A shows a block diagram of a muscle compression system accordingto an embodiment;

FIG. 1B shows a schematic diagram of muscle compression system accordingto an embodiment;

FIG. 2A shows a partial view of a compression segment according to anembodiment;

FIG. 2B shows multiple layers of a compression segment according to anembodiment;

FIG. 3A shows a compression apparatus of a muscle compression systemaccording to a sleeve configuration;

FIG. 3B shows a muscle compression system attached to a user's limb;

FIG. 3C shows a first side of muscle compression system according to afirst wrap configuration;

FIG. 3D shows a first side of a muscle compression system according to asecond wrap configuration;

FIG. 3E shows a second side of muscle compression system according to asecond wrap configuration;

FIG. 3F shows a top view of the muscle compression system according tothe wrap configuration;

FIG. 4 shows a flowchart of a method to compress a muscle of a limbaccording to an embodiment;

FIG. 5 shows another flowchart of a method to compress a muscle of alimb according to an embodiment;

FIGS. 6A and 6B show results realized by utilizing an embodiment of thesystem or method disclosed herein;

FIGS. 7A, 7B and 7C show graphs of Doppler ultrasound measurements ofthe blood flow in the popliteal artery without compression assistance,during unsynchronized compression assistance and during diastolic phasecompression assistance, respectively;

FIGS. 8A, 8B and 8C show graphs of venous flow at rest, during exerciseand based on compression assistance, respectively;

FIGS. 9A, 9B and 9C show graphs of arterial flow at rest, duringexercise and based on compression assistance, respectively;

FIGS. 10A, 10B and 10C show graphs of ultrasound measurements ofpopliteal arterial blood flow demonstrating the sustained impact ofproperly timed compression over 2-minute compression period, namely, ata first 10-second interval, a second 10-second interval and a last10-second interval, respectively;

FIG. 11 shows a graph of an electrocardiogram (ECG) signal correlated toflow of a popliteal artery velocity with timing of compression;

FIG. 12 shows a graph of timing of compression during diastolic phaseand when the muscle is in an inactive state;

FIG. 13 shows a wearer using a pair of compression systems on legsaccording to an embodiment; and

FIG. 14 shows a wearer using a muscle compression system on an armaccording to an embodiment.

DETAILED DESCRIPTION

Embodiments are described herein with reference to the attached figureswherein like reference numerals are used throughout the figures todesignate similar or equivalent elements. The figures are not drawn toscale and they are provided merely to illustrate aspects disclosedherein. Several disclosed aspects are described below with reference tonon-limiting example applications for illustration. It should beunderstood that numerous specific details, relationships, and methodsare set forth to provide a full understanding of the embodimentsdisclosed herein. One having ordinary skill in the relevant art,however, will readily recognize that the disclosed embodiments can bepracticed without one or more of the specific details or with othermethods. In other instances, well-known structures or operations are notshown in detail to avoid obscuring aspects disclosed herein. Theembodiments are not limited by the illustrated ordering of acts orevents, as some acts may occur in different orders and/or concurrentlywith other acts or events. Furthermore, not all illustrated acts orevents are required to implement a methodology in accordance with theembodiments.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope are approximations, the numerical values set forth inspecific non-limiting examples are reported as precisely as possible.Any numerical value, however, inherently contains certain errorsnecessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all sub-ranges subsumedtherein. For example, a range of “between 0 and 10” can include any andall sub-ranges between (and including) the minimum value of zero and themaximum value of 10, that is, any and all sub-ranges having a minimumvalue of equal to or greater than zero and a maximum value of equal toor less than 10, e.g., 1 to 4. In some instances, the range may havenegative values

Muscles require a continuous supply of oxygenated blood to properlyfunction and ward off fatigue (remove metabolic waste). The ability ofthe body to perform perambulatory motion for an extended period of timeis limited by various factors, some of which include genetics, physicalfitness level and cardiovascular efficiency. A subject has an ability toincrease oxygen introduced into the subject's body to a genetic maximumefficiency (VO_(2MAX)) through exercise and training. Once VO_(2MAX) isreached, the subject usually seeks to maintain this peak efficiency foras long as possible while continuing perambulatory motion. In thepresence of pathology, perambulatory motion can be made difficult by areduction in the circulation of blood and reduced delivery of oxygenatedblood.

During periods of inactivity or immobility, the continuous circulationof oxygenated blood throughout the body remains important forhomeostatic function. In specific instances of inactivity, the increasedcirculation of oxygenated blood can aid in future periods ofperambulatory motion and clinical treatment of a variety of diseases.This includes, but is not limited to, the removal of metabolic wasteproducts from localized tissue regions, amelioration of the symptoms ofmuscle fatigue, improved muscle performance in subsequent bouts ofexercise, and reducing the likelihood of thrombus formation. Forclinical treatments, increased circulation can prevent/reduce thelikelihood for thrombus formation, aid with wound healing, reduce edema,and reduce the stress on the cardiovascular system.

The apparatus, system and processes described herein provide assistanceto the wearer by reducing the effort the heart must perform to maintain,supplement, or enhance cardiovascular performance to accomplish a taskor work at hand.

The apparatus, system and processes described herein below provideassistance to the wearer by improving the local blood flow to the regionto aid in recovery after surgery.

The apparatus, system and processes described herein may be particularlyapplicable to soldiers, athletes, and other active individuals whodepend on good circulation to maintain cardiovascular performancesufficient to accomplish the task or work at hand. Thus, suchindividuals may benefit from being able to increase benefits achievedvia the activation of the skeletal muscle pump (muscle contraction).During periods when the muscle pump is inactive, individuals benefitfrom being able to maintain or exceed the circulatory benefits presentduring periods of perambulatory motion.

FIG. 1A shows a block diagram of an embodiment of a system 100A. Asillustrated, the system 100A may comprise a compression apparatus 110that is provided to apply pressure to a limb of a user. A limb may be aleg, such as a lower leg (such as, without limitation, beneath a knee ofthe user). In other embodiments, the limb may be an arm. The compressionapparatus 110 may be applied above the knee, as well.

The compression apparatus 110 may be a part of a wearable sleeve, sockor garment 115, which is configured to be worn, or fit around the limb.The compression apparatus 110 may comprise a smart material 112 such as,but not limited to, an electroactive polymer. In FIG. 1A, the smartmaterial 112 is represented as a fabric. Thus, in a non-limitingexample, the electroactive polymer may be integrated directly into awearable garment 115. The smart material 112 may include an artificialmuscle wherein an artificial muscle includes materials which maycontract in response to a stimulus such as electric current or voltageand expand in response to another stimulus or the removal of thestimulus. The terms smart material, electroactive polymer and artificialmuscle may be used interchangeably.

The compression apparatus 110 may be able to constrict, or applypressure, upon receiving an electrical signal to cause the compressionapparatus 110 to either constrict/contract or expand. A non-limitingexample of an amount of compression may be approximately 20-160 mmHgwherein “approximately” is used to mean plus or minus 10.

The system 100A may include a control system 140 having a controller142, as disclosed in more detail herein, may be set to a maximum appliedpressure within this range.

As explained in further detail below, timing and degree of compressionapplied by the compression apparatus 110 may be dictated by signalfeedback from at least one of physiological sensors and pressuresensors, respectively. The use of smart materials 112 allows foractuation of the compression apparatus 110 to occur fast enough to applycompression within a fraction of one cardiac cycle and repeatcompression during each cardiac cycle or a subset of heartbeats, inaccordance with the details of compression described herein. Theapplication of compression which occurs within one diastolic phase of acardiac cycle may be referred to as the “compression sequence.” Thecompression sequence will be described in more detail in relation toFIG. 3A.

The system 100A may include a plurality of sensors 120, 130 and 135.Sensor 120 hereinafter being referred to as a first sensor 120. Sensor130 hereinafter being referred to as a second sensor 130. Sensor 135hereinafter being referred to as a third sensor 135.

The first sensor 120 may be located on the limb. A non-limiting exampleof where the first sensor 120 may be located is in between the limb andthe compression apparatus 110. A non-limiting example of the firstsensor 120 may be a surface electromyography (“EMG”) sensor. The firstsensor 120 is also sometimes referred to as the muscle activity sensor.

The first sensor 120 may determine, in real-time, a contraction state,or activity, of a muscle in the limb. With the first sensor 120, muscleactivity may be determined by monitoring and recording electricalactivity associated with muscle contractions. As a non-limiting example,the first sensor 120 may be used to monitor electrical activity in alimb muscle, such as the calf muscles, specifically the gastrocnemiusand soleus muscles. In an embodiment, the limb muscle may be in thethigh, the upper arm or the forearm, for example.

The first sensor 120 may be wired or wireless and integrated into thewearable compression apparatus 110. Direct measurement of the electricalactivity of the muscle allows for clear determination of musclecontraction patterns, which may be used to determine a window of timewhen compression would be most beneficial. As a non-limiting example,during muscle contraction, intramuscular pressure is very high andexternal compression would not be capable of supplementing the actionsof the contracted muscle. In turn, external compression would be oflittle benefit while the calf muscle is contracted. The inventors havedetermined that external compression would be most beneficial when themuscle is relaxed, or in a non-contracted state, and intramuscularpressure is low.

In addition to analysis of muscle contraction, direct monitoring ofmuscle electrical signals facilitates the analysis of gait information.

In an embodiment, the first sensor 120 may indirectly identify muscleactivity, such as via an accelerometer to determine limb motion and timecompression based upon the readings from the accelerometer. The firstsensor 120 may include a plurality of sensors or sensor suite whereinthe collective data of the suite determines motion or non-motion of alimb to which compression is to be performed. The first sensor 120 mayinclude a force sensor, near infrared spectroscopy (NIRS) sensor, orelectromyography (EMG) sensor.

The second sensor 130 may be provided to measure, in real-time, thesystolic and diastolic time delay, cycle or rhythm, wherein themeasurement may be taken at the limb. The second sensor is sometimesreferred to as the cardiac cycle sensor. The second sensor 130 may be anon-invasive peripheral blood flow sensor such as, but not limited to, apulse photoplethysmograph (“PPG”) or near infrared spectroscopy sensor(NIRS). The second sensor 130 may be remote from the garment as will bedescribed later. Peripheral blood flow patterns of the user may be usedto set and modify the compression timing of the compression apparatus110 and makes the compression apparatus 110 customizable to the anatomyand physiology (such, as, but not limited to, vascular system) of theuser. More specifically, this measurement may provide for directlymeasuring arrival of the arterial pulse wave at the limb, which isdelayed relative to the timing of the cardiac contraction given bymeasurements of heart rate from an electrocardiogram (ECG). Such delaymay be due to height, physical condition, or heretical features of theuser. Thus, the pulse wave delay relative to the timing of the cardiaccontraction varies between individuals and further emphasizes theimportance of measuring local blood flow at the limb.

In an embodiment, the diastolic phase is a local diastolic phase in onecardiac cycle according to a limb to which compression is to be applied.

The third sensor 135 may be provided to measure compression to ensurethat an identified amount of pressure is actually being applied. Thethird sensor 135 may sometimes be referred to as the pressure sensor.The first sensor 120 and the second sensor 130 may be taking real-time,continuous readings of activity associated with the limb wherein thethird sensor 135 may be taking real-time, continuous readings eitherwhen compression is being applied or even when compressive phases arenot being applied. With respect to the plurality of sensors 120, 130 and135, when readings are made may be defined as information associatedwith each sensor may be collected for other reasons, such as, but notlimited to, other medical reasons.

The controller 142 may be in communication with the first sensor 120 andthe second sensor 130 to cause the compression apparatus 110 to apply apressure (compression) to the limb when both the diastolic phase of thelocal blood flow in the limb takes place and the muscle is in anon-contracted state. The controller 142 may comprise a processor 145such as, but not limited to, a microprocessor. Other parts of thecontroller 142 may be, but is not limited to, volatile memory 150,non-volatile memory 155, a transceiver 160, and algorithms 165, orcomputer program instructions, disclosed later herein. The controller142 or control system 140 may include a power source 162. In someembodiments, the power may be derived externally. For example, power maybe derived externally from a shoe as described in U.S. patentapplication Ser. No. 13/954,364 entitled “SYSTEM AND METHOD FORSUPPLEMENTING CIRCULATION IN A BODY” filed Jul. 30, 2013, and assignedto Lockheed Martin Corporation, which is incorporated herein byreference as if set forth in full. In other embodiments, the powersource 162 may include a battery source which may be rechargeable.

The controller 142 may also determine an amount of pressure to applywith the compression apparatus 110 to the limb. Thus, the controller 142may cause the compression apparatus 110 to vary an amount of pressureapplied to the limb based on a rate of blood flow desired in the limb.The third sensor 135 provides feedback to the controller 142 to vary thecompression of the compression apparatus 110 until it reaches the rightpressure.

In some embodiments, the algorithm 165 utilized in the controller 142may be used to identify a swing phase of walking by the user, when thecalf muscle is not contracted, based on the electrical activity and themuscle activity information will be used to determine the actions of thecompression system 100A. The algorithm 165 operated by the controlsystem 140 may be used to identify the local diastolic phase of thelocal blood flow pattern. Though a single algorithm is disclosed, thefunctions described may be performed by a plurality of algorithms.

The processor 145 may include any type of stationary computing device ora mobile computing device. The processor 145 may include one or moreprocessors. Depending on the exact configuration and type of computingdevice, system memory may be volatile (such as RAM), non-volatile (suchas read only memory (ROM), flash memory, and the like) or somecombination of the two. System memory may store an operating system, oneor more applications, and may include program data for performing theprocess of methods 400 and 500, described in detail below. The controlsystem 140 may carry out one or more blocks of methods 400 and 500. Thecontrol system 140 may also have additional features or functionality.For example, control system 140 may also include additional data storagedevices (removable and/or non-removable) such as, for example, magneticdisks, optical disks, or tape. Computer storage media may includevolatile and non-volatile, non-transitory, removable and non-removablemedia implemented in any method or technology for storage of data, suchas computer readable instructions, data structures, program modules orother data. System memory, removable storage and non-removable storageare all examples of computer storage media. Computer storage mediaincludes, but is not limited to, RAM, ROM, Electrically ErasableRead-Only Memory (EEPROM), flash memory or other memory technology,compact-disc-read-only memory (CD-ROM), digital versatile disks (DVD) orother optical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other physical mediumwhich can be used to store the desired data and which can be accessed bya processor. Any such computer storage media may be part of the controlsystem 140.

The control system 140 may also include or have interfaces for inputdevice(s) (not shown) such as a keyboard, mouse, pen, voice inputdevice, touch input device, etc. In an embodiment, the control system140 may store collected data from sensors and provide a cardiac analysisreport or performance analysis, such as related to any of the graphsdescribed herein.

The control system 140 may include a peripheral bus for connecting toperipherals. The control system 140 may contain communicationconnection(s) or transceiver 160 that allow the system 140 tocommunicate with other computing devices, such as over a network or awireless network. By way of example, and not limitation, communicationconnection(s) may include wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, radiofrequency (RF), infrared and other wireless media. The control system140 may include a network interface card to connect (wired or wireless)to a network.

Computer program code for carrying out operations described above may bewritten in a variety of programming languages, including but not limitedto a high-level programming language, such as C or C++, for developmentconvenience. In addition, computer program code for carrying outoperations of embodiments described herein may also be written in otherprogramming languages, such as, but not limited to, interpretedlanguages. Some modules or routines may be written in assembly languageor even micro-code to enhance performance and/or memory usage. It willbe further appreciated that the functionality of any or all of theprogram modules may also be implemented using discrete hardwarecomponents, one or more application specific integrated circuits(ASICs), or a programmed Digital Signal Processor (DSP) ormicrocontroller. A code in which a program of the embodiments isdescribed can be included as a firmware in a RAM, a ROM and a flashmemory. Otherwise, the code can be stored in a tangiblecomputer-readable storage medium such as a magnetic tape, a flexibledisc, a hard disc, a compact disc, a photo-magnetic disc, a digitalversatile disc (DVD).

In the embodiment of FIG. 1A, the compression apparatus 110 may includean electromagnet device in lieu of smart material 112, where theelectromagnet device being configured to cause compression in responseto an electrical stimulus. In an embodiment, the compression apparatus110 may include a pneumatic device or mechanical device to perform thecompression. In such configurations, the compression apparatus 110 wouldreceive a source of pneumatic fluid (air or liquid) under the control ofcontrol system 140. Furthermore, the system 100 may include a pneumaticfluid source (not shown).

In an embodiment, the controller 142 may vary the voltage or currentsupplied to the artificial muscle, smart material or electromagnet. Inanother embodiment, the controller 142 may vary a working or pneumaticfluid channeled to bladders of the compression apparatus 110.

Hybrid configurations may be implemented. A non-limiting example, ahybrid configuration may include structural instabilities to exploitrapid transition between two states, as with snap-actuators.Alternatively, combined electromagnetic/hydraulic systems can beimplemented including, but not limited to, magneto-reactive fluids orsolenoid pistons.

FIG. 1B shows a schematic diagram of a muscle compression systemaccording to an embodiment. Each segment 112B of the compressionapparatus 110B may comprise connections to a data, power and/orcompression timing bus 144B from the control system 140B. Each segment112B of the compression apparatus 110B connects to the data, power andcompression bus 144B. The bus 144B may include a single line or multiplelines to permit communications between each segment (denoted at 110B)and the control system 140B. Communications may include sensor datatransferred from sensors 120B and 135B from the segment to the controlsystem 140B. Communications may include the transfer of a current orvoltage such as an electrical stimulus to activate the segment such asthe artificial muscle, represented as cross-hatched to denote a fabric,threads or an electroactive polymer. The communication protocol used mayprovide rapid access to each segment on a one-by-one basis by thecontrol system 140B. The bus 144B may provide power to the plurality ofsensors 120B, 130B and 135B. Each segment may sometimes be referred toas a compression cuff. The segment may completely surround the limbmuscle or partially surround the limb muscle.

The plurality of sensors 120B, 130B and 135B are represented as dashedline circles. The sensors 120B and 135B may be integrated in an activelayer within the segments, as will be described in more detail. Whilethe sensors 120B and 135B are represented as dashed lines, in eachsegment, one or more of the sensors may be omitted. For example, not allsegments may require a muscle activity sensor. Therefore, the layers ofthe segments may vary.

The sensor 130B is represented separate from the segments of thecompression apparatus 110B. However, the sensor 130B in an embodiment isintegrated into the garment 115 (FIG. 1A) at a location which allows thecardiac cycle to be sensed.

FIG. 2A shows a partial view of a compression segment of the compressionapparatus 110 according to an embodiment. The compression apparatus 110may comprise multiple layers of materials such as, but not limited to,two layers of materials. As illustrated a layer closest to the limb maybe or comprise the sensor 135 which is provided to measure an actualpressure being applied. An outer, or second layer, may be or comprisethe electroactive polymer, or smart material 112.

FIG. 2B shows multiple layers of a compression segment 212B according toan embodiment. Each of segments 212B may comprise a data, power and/orcompression connection to the control system 140B. Each segment 212Bconnects to a data, power and compression bus. The segment 212B is amodular segment. As shown in FIG. 2B, the segment 112 (FIG. 1A) includestwo layers.

The modular segment 212B may have a plurality of layers that can bevaried based on the application needs. The segment 212B includes aplurality of active layers 280. The active layers include layers 282,284 and 286. There can be more or less layers used as dictated by theapplication. Additionally, some layers as shown can be implemented as asingle “physical” layer or with portals through layers connectingelement layers together. For example, layer 282 may be a muscle activitysensor layer which may serve as the muscle activity sensor. Layer 284may be a pressure sensor layer which may serve as the pressure sensor.Layer 286 may be a compression layer which may include an artificialmuscle, for example.

In the illustration, layers 275 and 290 are shown sandwiching the activelayers 280 and may be part of the garment 115 (FIG. 1A). The layer 275may be an inside or interior layer wherein the inside or interior layerbeing in direct contact with the skin of the wearer. Layer 290 may be anexterior layer.

In an embodiment, the pressure sensor layer (i.e., layer 284) and muscleactivity sensor layer (i.e., layer 282) might be integrated into asingle physical layer or single physical unit. As an additional example,the muscle activity sensor layer (i.e., layer 282) and the inside orinterior layer 275 might be integrated so that elements of the sensorpass through the layer 275 to make skin contact. The active layers 280may be enclosed by layers 275 and 290 which protect the wearer and theactive layers such as from sweat from the wearer and moisture in theenvironment, for example. One implementation of the layers 275 and 290integrate all necessary active layers. In some embodiments, thecompression layer 286 may move separately from any of the other layerswherein the compression layer 286 provides a compressive force to thelimb it is wrapped around.

FIG. 3A shows a compression apparatus 310A of a muscle compressionsystem according to a sleeve configuration. As shown, the compressionapparatus 310A may have a plurality of compression segments 305A, 306A,307A, and 308A. Instead of each segment 305A, 306A, 307A, and 308Acompressing at the same time, compression takes place according to acompression sequence. The compression sequence may begin at the (first)segment 305A furthest from a heart of the user and conclude at the(last) segment 308A closest to the heart of the user during the localdiastolic phase of the blood flow. Compression on any intermediatesegments 306A and 307A follows in a similar sequence between the firstsegment 305A and the last segment 308A. While the embodiment illustratesfour segments, the apparatus 310A may have more or less segments. Duringcompression, the segment constricts to exert a force of pressure on thelimb or limb muscle. Compression is released or terminated after thecompression sequence, upon detection of the end of the diastolic phaseof the cardiac cycle.

The third sensor 135 may be provided for each segment 305A, 306A, 307A,and 308A so that pressure may be measured for each compression to ensurethat compression reaches a desired pressure for each segment.

The sleeve configuration generally surrounds the limb and maintains itsposition on the limb during a non-compression state. The sleeve isgenerally continuous with the circumference varied to accommodate theanatomical profile of a portion of the limb whether the calf, thigh,upper arm or forearm. In an embodiment, the compression segments may beintegrated into a sock. In a sock configuration, the compressionsegments may be located in the portion which fits around the calf andabove the ankle.

FIG. 3B shows another embodiment of a backside of the compressionapparatus 310B. As illustrated in FIG. 3B, the segments may not form acontinuous compression apparatus 310B as disclosed in FIG. 3A. Instead,each segment 305B, 306B, 307B and 308B may be an individual strip withtabs 350 which can be sized to fit a user using hook and loop fasteningassemblies 352 and 355. The strip can be tightened around the limb for asnug fit. The strip may be layered as described in FIG. 2B.

Though both FIG. 3A and FIG. 3B show multiple segments where a milkingpattern is utilized (as represented by the arrow in between 1 and 4),these embodiments are not meant to be limiting. In another non-limitingexample, a different compression sequence may be utilized. For example,the compression sequence may include activating for compression segments305A and 307A, together or in series; or segments 306A and 308A togetheror in series. The compression sequence may repeat at least once or untilthe diastolic phase is complete in the current cardiac cycle or muscleactivity is sensed. The compression sequence may be varied based on theexpected duration of the diastolic phase wherein the diastolic phase mayvary such as the result of the intensity of activity of the wearer.Thus, the compression sequence may be synchronized to the diastolicphase.

In yet another non-limiting example, the compression apparatus 310A or310B may not have multiple compression segments, but may have a singlecompression segment. The single compression segment may exert a force ofpressure for a duration of the diastolic phase. The single compressionsegment may exert a force of pressure which is applied and then relaxedrepeatedly for the duration of the diastolic phase or until muscleactivity is sensed.

In the embodiment of FIG. 3B, the second sensor 130 (FIG. 1A) may beattached to the limb from or through the apparatus.

In a non-limiting example, the amount of compression for each segmentmay vary based on blood flow measured with the second sensor 130. Morespecifically, each segment may be compressed based on local arterialblood flow and local muscle activation. Thus, compression per segmentmay be provided only when the monitored readings identify whencompression is most beneficial. Though compression is to be performedduring the diastolic phase, compressive subsets may be performed duringthis phase. As a non-limiting example, a rate of compression may be at alevel to provide for two complete compressive cycles (compressionsequence) of the segments to occur. In another non-limiting example,only a smaller subset of segments may be utilized.

Monitoring the amount of pressure applied may be done with thecontroller 142 employing a real time data processing to monitorphysiological parameters such as, but not limited to, heartbeats andmechanical parameters such as, but not limited to, applied pressure, inorder to control when and how much pressure is applied to the limb. Realtime data processing may involve continuous monitoring of the appliedpressure and comparison to a pre-set maximum applied pressure. Thisensures that the desired operating pressure is achieved for eachcompression and compression is ceased once this threshold is met.

Thus, as illustrated above, an apparatus may be provided for applyingexternal compression to the limb of the user based on real-time readingsregarding a cardiac cycle of the user measured at the limb and musclecontractions measured at the limb. Compression is applied when both thelocal blood flow is in a diastolic phase, as measured on the limb, andthe muscle is in a non-contracted state. The smart material such as, butnot limited to, an electroactive polymer is a part of the apparatus andwhich provides for the actual compressive effect. In an embodiment, theartificial muscle is at least partially located around the limb, namely,at a backside and along sides of the limb. When the limb is a leg, theartificial muscle wraps around the gastrocnemius and soleus muscleslocated on the backside of the leg. More specifically, with respect tothe leg, circumferential pressure may be preferred.

FIG. 3C shows a first side of muscle compression system 300C accordingto a first wrap configuration. As a wrap, the garment 315C may besecured to a limb using hook-and-loop fastening straps 350 with hook andloop fasteners 352 and 355. The hook and loop fasteners 352 and 355 maybe substituted with other fasteners, such as without limitation,zippers, adhesives, tapes, external flexible bandages, etc.

The muscle compression system 300C includes a plurality of active layers380 embedded or sandwiched between layers 373 and 390 with layer 390partially removed to show the underlying layers of the active layer 380and the layer 375. Between the segments, gaps 360 are provided. The gap360 may represent the absence of material. The active layers 380 mayinclude sensors 320 or 335 denoted by the dashed circle. The sensor maybe integrated into the layers or a separate element. As also describedpreviously, one or more sensors may be omitted for a particular segment.

The control system 340 communicates with the active layers 380 and/orsensors 320 and 335. In this embodiment, the sensor 330 is omitted, butmay be included. For example, in some embodiments, the cardiac cyclesensor 330 may be remote from the garment 315C so that the cardiac cyclemay be sensed elsewhere on the wearer's body. Hence, the remote cardiaccycle sensor would communicate with the control system 340 to providethe cardiac cycle timing so that the compression sequence can bederived.

The number of segments may vary. The length of the segment is shorterthan the width of the garment. However, the length of the segment shouldallow a compression effect on the limb or limb muscle to be realizedwhen worn. The segment is represented as an elongated rectangularmember. The width of the garment corresponds to the dimension whichwraps around the circumference of the limb.

The width of the wrap may also enable the system to be sized fordifferent wearer body types as well as applicability to different limbs(i.e. calf, thigh, forearm, and upper arm).

FIG. 3D shows a first side of a muscle compression system 300D accordingto a second wrap configuration. In this configuration, the gaps 360 havebeen omitted and the cardiac cycle sensor 330 is shown embedded in thegarment between the layer 375 and layer 390. The sensor 330 is shown atthe top of the garment 315D.

FIG. 3E shows a second side of muscle compression system 300E accordingto a second wrap configuration with a portion of layer 375 removedexposing a portion of a segment with active layers 380 and layer 390.

FIG. 3F shows a top view of the muscle compression system 300F accordingto a wrap configuration. The compression system 300F is in a wrapped orinstalled state around a limb. The modular segments take up a part orall of the circumference of the garment wrap 315F. The wrap itself maynot completely surround a limb, but rather have the fasteners tocomplete the loop around the limb. The hook-and-loop fastening straps350 may go completely around the garment 315F or may be only a smallsize to close the loop, as shown. The modular segments are surrounded bythe layers 390 and 375 and the system 300F is held in place byhook-and-loop fastening straps 350 (or other methods as describedpreviously). The external layer 390 is inelastic and does not stretch.When the compression layer in the active layer 380 is activated, theexternal layer 390 directs the compression inwards towards the limbbeing compressed, in the direction of the arrows shown.

FIG. 4 shows a flowchart of a method 400 to compress a muscle of a limbaccording to an embodiment. The methods and processes shown herein arefor illustrative purposes and represented in a series of blocks. Theblocks may be performed sequentially in the order shown or in adifferent order. One or more of the blocks may be performedcontemporaneously. Furthermore, one or more of the blocks may be addedor omitted.

In some embodiment, the system 100A is worn during motion of the usersuch as during work or sports activities. In some embodiment, system100A may be used such as while a user is sleeping. However, whilesleeping, the user may get up or may move their legs. Thus, as will beapparent from the description herein, the compression is not appliedduring muscle movement, activity or contraction. In some embodiments,the compression is only applied for the fraction of time in the cardiaccycle that relates to the diastolic phase or period.

As illustrated, the method 400 comprises monitoring, or measuring,peripheral blood flow, namely, blood flow, at block 410. In anembodiment, the blood flow may be measured locally at the limb. In anembodiment, the blood flow may be measured at the heart. Based on themonitoring, at block 410, a determination is made when the cardiac cycleis either in a diastolic phase or at the end of a systolic phase, atblock 420. If the blood flow is measured locally, the local diastolicphase (or end of a systolic phase) is used to directly synchronize thecompression timing. If the blood flow is measured at the heart of thewearer/user such as by a remote cardiac cycle sensor, a delay is used tosynchronize timing of the compression to the local diastolic phaserealized at the limb. If the diastolic phase is not detected at block420, the method loops back to block 410.

If the diastolic phase is detected based on the determination at block420, monitoring of muscle activity of the limb occurs, at block 430. Adetermination is made if the muscle is activated, or in a contractedstate, at block 440. If the muscle is not contracted, or in anon-activated (or relaxed) state, compression occurs, at block 450. Ifin a contracted state or the muscle is detected as being activated, nocompression occurs and the method loops back to block 410. In otherwords, the compression timing synchronization to a local diastolic phaseis essentially aborted/terminated. However, cardiac cyclemonitoring/sensing and muscle activity may be performed essentiallycontinuously. Block 450 loops back to block 410.

In operation, the compression sequence may be repeated such thatmultiple compression sequences are used in a single diastolic phase orthe compression sequence may be one sequence to terminate at or near theend of the diastolic phase.

The method may be supplemented with additional blocks related to thesensing/monitoring of the pressure being applied by the compression cuffwherein the compression effect caused by the compression apparatus maybe varied based on the pressure sensing readings.

FIG. 5 shows another flowchart of a method. As illustrated the method500 provides for monitoring, in real-time, peripheral blood flow at alimb of a user with at least a first sensor attached at the limb, atblock 510. The method 500 also comprises determining, in real-time withat least the first sensor, when the heart of the user is in a diastolicphase based on the monitored blood flow at the limb, at block 520. Ifthe peripheral blood flow is determined to be in a diastolic phase, themethod 500 further comprises determining, in real-time, whether a musclein the limb is in a non-contracted state with at least a second sensor,at block 530. If the muscle is in the non-contracted state, the methodfurther comprises applying pressure to the muscle with a compressionapparatus as initiated by a controller, at block 540.

The method may further comprise measuring pressure applied by thecompression apparatus to ensure that a correct amount of pressure isapplied during compression, at block 550. The method 500 may furthercomprise analyzing when the muscle is in the non-contracted state tofurther determine when to apply pressure to the muscle, at block 560. Ascan be appreciated one or more of the blocks may be performedcontemporaneously with other blocks. Furthermore, the order may bemodified.

Applying pressure (compression) to the muscle with the compressionapparatus may further comprise, during the diastolic phase, applyingpressure in a sequence with the compression apparatus having a pluralityof sections individually compressible which apply pressure in a sequencewhere a first section furthest from the heart is contracted, orcompressed, first and a last section that is closest to the heart iscontracted, or compressed, last.

Thus, in operation, each individual compression may be based oninformation garnered from sensors measuring local arterial blood flowand muscle activation. This information may be used as input to a realtime control system, as part of a controller, to quickly react tochanges in physiological behavior and determine when compression shouldbe applied. Further, the timing of compression based on local arterialblood flow allows for independent timing for each limb based on currentlocal conditions. The timing of compression may be relative to eachheartbeat, but can also be customized to a subset of heartbeats such as,but not limited to, compressions every other heartbeat. The limb will beactively compressed only after the completion of the systolic phase ofthe localized blood flow. That is, compression will occur during thediastolic phases of the local blood flow. No external compression wouldbe applied during the systolic portion.

When actual compression occurs is important based on physiological andenergy usage reasons. Regarding the physiology based reasoning, timingwill prevent a potential increase in cardiac afterload, which is thepressure the left ventricle must overcome to eject blood from the heart,and disruption of blood flow into the limb. Peripheral blood flowinformation will be used in conjunction with information garnered frommuscle activity sensors as input into the timing control for thecompression system. It is noted that diastolic phases of the local bloodflow may not necessarily align with the periods of calf or limb musclerelaxation. In turn, it may be advantageous to apply compression onlywhen muscle relaxation occurs simultaneously with the diastolic phase ofthe local blood flow. This triggering based on this timing cycle wouldrequire the monitoring of both the flow cycle and limb muscle activityto determine the initiation of compression. As for the energy usagereason, by applying compression only when it will have the mostphysiological benefit, energy used by the compression system can bereduced. As a non-limiting example, compression during muscle activitydoes not have physiological benefit, so energy is conserved by delayingcompression until muscle contraction has ended.

FIGS. 6A and 6B show results realized by utilizing an embodiment of thesystems or methods disclosed herein. The results are illustrated asultrasound waves measured at the leg in the popliteal artery. As shownin FIG. 6A, when no compression is applied, at 605, a systolic peak,denoted by arrow 620, is higher (more blood is flowing) than at thediastolic peak (less blood is flowing as the heart is relaxed), denotedas arrow 630. When compression is applied, at 607 during the diastolicphase of the cardiac cycle, blood flow is then increased during thediastolic phase. FIG. 6B illustrates the effects of the increased bloodflow continues even after 2 minutes of compression, during the diastolicphase. Arrows 630 are represented in dashed lines while arrows 620 aresolid.

As is also illustrated in FIGS. 6A and 6B, a top line 610 shows theheart rate measured at the heart, namely, not on the limb. Themeasurements below the top line 610 are taken at the limb. As explainedabove, the measurements at these different locations indicate a timeshift between the contraction of the heart and arrival of the systolicpulse wave locally at the limb, which will be unique person to person.This further illustrates why measuring local blood flow at the limb ispreferred.

FIGS. 7A, 7B and 7C show graphs 700A, 700B and 700C of Dopplerultrasound measurements of the blood flow in the popliteal arterywithout compression assistance, during unsynchronized compressionassistance and during diastolic phase compression assistance,respectively. The benefits of compressing during the diastolic portionof the local cardiac cycle as outlined in this patent is demonstratedvia the examination of changes in blood delivery to the calf region.While the graphs are directed to the leg/limb and calf region, themuscle compression system may be used on the arm muscles, such as in theupper arm or forearm.

In FIG. 7A, a Doppler ultrasound measurement of the blood flow in thepopliteal artery is shown, which is the main conduit artery supplyingblood flow to the calf region, without the application of compression.The solid arrows 720A indicate the systolic peaks, indicative of bloodflow into the lower limb that is driven by the contraction of the heart.The dashed arrows 730A indicate the diastolic phase in which blood flowhas slowed into the leg.

During this phase, the contraction of the heart has ceased andventricular refilling is occurring (blood is returning to the heart)

FIG. 7B shows the augmentation of the popliteal artery blood flow withthe application of compression to the calf region. The compression isapplied during every heartbeat, but timed predominately during thesystolic phase (outside of the local diastole phases). The solid arrows720B indicate a reduction in blood flow into the leg with eachcontraction of the heart. This has two main detrimental effects on thecardiac and lower limb muscle function. The first effect is the bluntedsystolic peak indicates a potential increase in cardiac afterload, whichis the pressure the left ventricle must overcome to eject blood from theheart. Over time, this can put stress on the heart as it pumps harder toovercome the resistance to flow imparted by improper compression timing.The second effect is that the reduction of blood flow into the lowerlimb reduces the availability of oxygenated blood to the leg muscles.

Many devices on the market now apply compression at a time intervalirrespective of the physiological signals, such as the cardiac cycle,which can reduce circulation and in some cases increase the likelihoodof blood pooling and clotting in the lower limbs.

FIG. 7C shows the augmentation of the popliteal artery blood flow due tothe application of compression based on the timing algorithm outlined inthis patent. Specifically, the compression is applied during the localdiastolic phases. The solid arrows 720C indicate the higher systolicpeak and the dashed arrow 730C indicate the significantly increaseddiastolic flow with our compression technique. Overall, the oxygenatedblood delivered to the calf muscle is increased within a cardiac cycleincreasing the efficiency of the heart and reducing heart rate as aresult of increased cardiac output with each contraction. The increasedcirculation in the leg helps to remove metabolic waste products that cancause muscle fatigue and soreness.

The benefits of compression such as during exercise can be evident fromthe description and graphs below. The exercise conducted includedapplication of pressure on a foot pedal.

FIGS. 8A, 8B and 8C show graphs 800A, 800B and 800C of venous flow atrest, during exercise and based on compression assistance, respectively.The timing of compression with physiological signals and feedbackregarding muscle activity has been shown to be beneficial. The venousblood flow (blood flow back to the heart) velocity profile showed largechanges with exercise and with the application of compression. In thegraphs of FIGS. 8B and 8C, the contraction (active) states 805B, 805C,809B and 809C of the muscle and the relaxed (inactive) states 807B and807C of the muscle are marked or demarcated by the vertical dashedlines.

FIGS. 9A, 9B and 9C show graphs of arterial flow 900A, 900B and 900C atrest, during exercise and based on compression assistance, respectively.In the graphs of FIGS. 9B and 9C, the contraction (active) states 905B,905C, 909B and 909C of the muscle and the relaxed (inactive) states 907Band 907C of the muscle are marked or demarcated by the vertical dashedlines.

With the depression of a weighted foot pedal, the muscle pump wasactivated resulting in increased popliteal venous blood flow (FIG. 8B)as would normally happen during walking. During the relaxation phase807B when the pedal is not pressed, venous flow decreases and bloodpools in the leg/limb. In contrast, when active compression was applied,timed to the periods in which the muscle pump is not active and duringthe diastolic phase of the cardiac cycle, venous flow was increasedduring the resting phase of exercise with each compression 807C (FIG.8C). Again, work is reduced for the heart due to more blood returned andexpelled for each beat and active compression aids in venous return whenthe muscle pump is “off.” On the arterial side (FIG. 9C), circulation isincreased during the relaxation phase active state of exercise with theproper timing of compression (the periods in which the muscle pump isnot active and during the diastolic phase of the cardiac cycle) 907C.

FIGS. 10A, 10B and 10C show graphs 1000A, 1000B and 1000C of ultrasoundmeasurements of popliteal arterial blood flow demonstrating thesustained impact of properly timed compression over a 2-minutecompression period, namely, at a first 10-second interval, a second10-second interval and a last 10-second interval, respectively. At1005A, a baseline is shown in the ultrasound measurements. At 1015A, anincrease in the peak velocity is shown.

In FIG. 10B, a decrease in peak velocity is shown in 1017B with a steadystate represented at arrow A 10.

FIG. 11 shows a graph 1100 of an electrocardiogram (ECG) signal 1105Acorrelated to flow of a popliteal artery velocity 1105B with timing ofcompression represented as lines 1109. The graph 1100 represents thetiming of compression 1109 relative to the ECG signal 1105A measured atthe heart and the local peripheral blood flow 1105B measured usingDoppler ultrasound at the compression site on the leg. The compressionoccurs during the local diastolic phase of the local blood flow avoidingthe systolic phases. The pulse wave delay period PWD is noted on thegraph to represent the difference in local and remote diastolic phasecommencements.

FIG. 12 shows a graph 1200 of timing of compression during diastolicphase and when the muscle is in an inactive state of a wearer. The graphwill vary based on muscle activity assuming that the diastolic phaseessentially repeats itself after the systolic phase according to thesame time interval. The graph 1200 represents the timing of compression(lines), denoted as numeral 1209, during light exercise (pressing a footpedal) represented in a dashed line, denoted at 1207. The graph 1200indicates the application of compression 1209 only during the periodwhen the pedal is not pressed (muscle is not activated/being used). Thetiming is shown in reference to the ECG signal 1205A measured at theheart indicating compression occurs late in the cardiac diastolic phaseto account for the pulse wave time delay, denoted as PWD in FIG. 11, tothe compression site on the leg/limb. In an embodiment, the compressioncycle would be synchronized according to the local diastolic phaseaccording to the local timing realized in the limb. If the diastoliccycle measurements are taken remote from the limb to be compressed, thePWD pulse wave time delay PWD should be compensated for in order tosynchronize the measurements of the cardiac diastolic cycle to the localdiastolic cycle.

FIG. 13 shows a wearer using a pair of compression systems 1300 on legsaccording to an embodiment. In some embodiment, the wearer may want touse only one system 100A on one limb such as for recovery after surgeryor for other applications. In some embodiments, the wearer may want touse two systems 100A of FIG. 1A, represented as system 1300, or otherconfigurations described herein, on each leg. The wearer may use two ormore systems 100A according to their needs on their limbs. In some pairsof systems 100A, one or more components of the control system on onelimb may be eliminated.

FIG. 14 shows a wearer using a muscle compression system 1400 on an armaccording to an embodiment. The system 1400 is installed below theelbow. Nonetheless, the system 1400 may be worn above the elbow on theupper arm.

From a military, athletic, and physical laborer perspective, increasedendurance, reduced fatigue and faster recovery times after physicalactivity may be realized. Those who sit for extended periods of time,such as, but not limited to, unmanned aerial vehicles (“UAV”) pilots,extreme video garners who sit for extended durations, etc., may benefitfrom reduced blood pooling in their lower extremities. Air travelers mayalso benefit from a reduced risk of deep vein thrombosis (“DVT”).Airlines could supply embodiments disclosed herein to all passengers asthey board an aircraft. The rhythmic compression helps blood continuecirculating in the lower extremities and should reduce the risk of DVT.Embodiments may also be used by individuals in space to reduce loss ofmuscle mass when remaining in outer space for an extended period oftime.

The “step-by-step process” for performing the claimed functions hereinis a specific algorithm, and may be shown as a mathematical formula, inthe text of the specification as prose, and/or in a flow chart. Theinstructions of the software program create a special purpose machinefor carrying out the particular algorithm. Thus, in anymeans-plus-function claim herein in which the disclosed structure is acomputer, or microprocessor, programmed to carry out an algorithm, thedisclosed structure is not the general purpose computer, but rather thespecial purpose computer programmed to perform the disclosed algorithm.

A general purpose computer, or microprocessor, may be programmed tocarry out the algorithm/steps for creating a new machine. The generalpurpose computer becomes a special purpose computer once it isprogrammed to perform particular functions pursuant to instructions fromprogram software of the embodiments described herein. The instructionsof the software program that carry out the algorithm/steps electricallychange the general purpose computer by creating electrical paths withinthe device. These electrical paths create a special purpose machine forcarrying out the particular algorithm/steps.

In particular, unless specifically stated otherwise as apparent from thediscussion, it is appreciated that throughout the description,discussions utilizing terms such as “processing” or “computing” or“calculating” or “determining” or “displaying” or the like, refer to theaction and processes of a control system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch data storage, transmission or display devices.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.Furthermore, to the extent that the terms “including,” “includes,”“having,” “has,” “with,” or variants thereof are used in either thedetailed description and/or the claims, such terms are intended to beinclusive in a manner similar to the term “comprising.” Moreover, unlessspecifically stated, any use of the terms first, second, etc., does notdenote any order or importance, but rather the terms first, second,etc., are used to distinguish one element from another.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which embodiments belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

While various disclosed embodiments have been described above, it shouldbe understood that they have been presented by way of example only, andnot limitation. Numerous changes, omissions and/or additions to thesubject matter disclosed herein can be made in accordance with theembodiments disclosed herein without departing from the spirit or scopeof the embodiments. Also, equivalents may be substituted for elementsthereof without departing from the spirit and scope of the embodiments.In addition, while a particular feature may have been disclosed withrespect to only one of several implementations, such feature may becombined with one or more other features of the other implementations asmay be desired and advantageous for any given or particular application.Furthermore, many modifications may be made to adapt a particularsituation or material to the teachings of the embodiments withoutdeparting from the scope thereof.

Therefore, the breadth and scope of the subject matter provided hereinshould not be limited by any of the above explicitly describedembodiments. Rather, the scope of the embodiments should be defined inaccordance with the following claims and their equivalents.

We claim:
 1. A device comprising: a wearable garment; a compressionapparatus embedded in the garment for applying an external compressionto a limb of a user; and at least one of a processor or a controllerconfigured to control the compression apparatus to apply the externalcompression, according to a compression sequence, to a muscle of thelimb of the user based on real-time measurements regarding a cardiaccycle having a diastolic phase and systolic phase of the user andreal-time measurements of muscle activity wherein the compressionsequence is synchronized to commence when both a local blood flow at thelimb is in the diastolic phase and the muscle is in a non-contractedstate.
 2. The device as set forth in claim 1, wherein the compressionapparatus comprising a pressure sensor to sense an amount of pressureapplied during compression.
 3. The device as set forth in claim 1,wherein: the wearable garment comprises a wearable sleeve that fitsaround the limb; and the compression apparatus comprises a plurality ofcompression segments, each compression segment comprising an artificialmuscle integrated in the wearable sleeve which in response to anelectrical stimulus causes a compression state or an expansion state. 4.The device set forth in claim 3, wherein the compression sequenceactivates the plurality of compression segments beginning at a firstcompression segment of the plurality of compression segments beingfurthest from the heart of the user and concludes with a lastcompression segment of the plurality of compression segmentscorresponding to a location on the limb closest to the heart of theuser, during the diastolic phase of the local blood flow.
 5. The deviceset forth in claim 3, further comprising a plurality of sensors, theplurality of sensors comprising: a cardiac cycle sensor to perform thereal-time measurements regarding the cardiac cycle having the diastolicphase and systolic phase of the user directly at the limb; and a muscleactivity sensor to perform the real-time measurements of musclecontractions.
 6. The device set forth in claim 5, further comprising apressure sensor to sense an amount of pressure exerted by eachcompression segment of the plurality of compression segments of thecompression apparatus.
 7. The device set forth in claim 6, wherein theat least one of a processor or a controller is configured to determinethe commencement of the compression sequence; and each compressionsegment comprising: a plurality of active layers in electricalcommunication with the at least one of a processor or a controller, theplurality of active layers being the pressure sensor, the artificialmuscle and the muscle activity sensor.
 8. A system comprising: awearable garment to be worn on a limb of a user; a cardiac cycle sensorto perform real-time measurements regarding a cardiac cycle having adiastolic phase and systolic phase of the user; a muscle activity sensorto perform real-time measurements of muscle contractions on the limb; acompression apparatus embedded in the garment for applying an externalcompression to the limb of the user; and at least one of a processor ora controller coupled to the compression apparatus configured to controlthe compression apparatus to apply pressure, according to a compressionsequence, to a muscle of the limb based on the real-time measurements ofthe cardiac cycle of the user and the real-time measurements of themuscle contractions wherein the compression sequence is synchronized tocommence when both a local blood flow at the limb is in the diastolicphase and the muscle is in a non-contracted state.
 9. The system setforth in claim 8, wherein the compression apparatus comprises a pressuresensor to sense an amount of pressure applied during compression. 10.The system set forth in claim 8, wherein: the wearable garment comprisesa wearable sleeve that fits around the limb; and the compressionapparatus comprises a plurality of compression segments, eachcompression segment comprising an artificial muscle integrated in thewearable sleeve which in response to an electrical stimulus causes acompression state or an expansion state.
 11. The system set forth inclaim 10, wherein the compression sequence activates the plurality ofcompression segments beginning at a first compression segment of theplurality of compression segments being furthest from the heart of theuser and concludes with a last compression segment of the plurality ofcompression segments corresponding to a location on the limb closest tothe heart of the user, during the diastolic phase of the local bloodflow.
 12. The system set forth in claim 10, wherein the cardiac cyclesensor being integrated in the wearable garment and in communicationwith the at least one of a processor or a controller.
 13. The system setforth in claim 11, each compression segment comprising: a plurality ofactive layers being in electrical communication with the at least one ofa processor or a controller, the plurality of active layers being apressure sensor, the artificial muscle and the muscle activity sensor.14. The system set forth in claim 8, further comprising: a secondwearable garment to be worn on a second limb of the user; a secondcardiac cycle sensor to perform real-time measurements regarding acardiac cycle having a diastolic phase and systolic phase of the user inthe second limb; a second muscle activity sensor to perform real-timemeasurements of muscle contractions in the second limb; a secondcompression apparatus embedded in the second garment for applying anexternal compression to the second limb of the user; and at least one ofa second processor or a second controller coupled to the secondcompression apparatus configured to control the second compressionapparatus to apply pressure, according to a second compression sequence,to a muscle of the second limb based on the real-time measurements ofthe cardiac cycle of the user associated with the second limb and thereal-time measurements of the muscle contractions of the second limbwherein the second compression sequence is synchronized to commence whenboth the local blood flow at the second limb is in the diastolic phaseand the muscle in the second limb is in a non-contracted state.
 15. Amethod comprising: sensing, by a cardiac cycle sensor, real-timemeasurements regarding a cardiac cycle having a diastolic phase andsystolic phase of a user, sensing, by a muscle activity sensor,real-time measurements of muscle contractions in a limb of the user;applying compression, by a compression apparatus, to a muscle in thelimb of the user; and controlling the compression, by a processorcoupled to the compression apparatus, according to a compressionsequence, based on the real-time measurements of the cardiac cycle ofthe user and the real-time measurements of the muscle contractionswherein the compression sequence is synchronized to commence when both alocal blood flow at the limb is in the diastolic phase and the muscle isin a non-contracted state.
 16. The method set forth in claim 15, furthercomprising: sensing, by a pressure sensor, an amount of pressure appliedduring compression wherein the compression is varied in response to thesensed pressure.
 17. The method set forth in claim 15, wherein: thecompression apparatus comprises a plurality of compression segments,each compression segment comprising an artificial muscle integrated in awearable garment which in response to an electrical stimulus supplied bythe processor causes a compression state or an expansion state.
 18. Themethod set forth in claim 17, wherein the compression sequence activatesthe plurality of compression segments beginning at a first compressionsegment of the plurality of compression segments being furthest from theheart of the user and concludes with a last compression segment of theplurality of compression segments corresponding to a location on thelimb closest to the heart of the user, during the diastolic phase of thelocal blood flow.
 19. The method set forth in claim 15, wherein eachcompression segment comprises a plurality of active layers being inelectrical communication with the processor, the plurality of activelayers being a pressure sensor, the artificial muscle and the muscleactivity sensor.
 20. The method set forth in claim 15, furthercomprising: sensing, by a second cardiac cycle sensor, real-timemeasurements regarding a cardiac cycle having a diastolic phase andsystolic phase of the user in a second limb; sensing, by a second muscleactivity sensor, real-time measurements of muscle contractions in thesecond limb; applying compression, by a second compression apparatus, tothe second limb of the user; and controlling, by a second processor, thecompression by the second compression apparatus, according to a secondcompression sequence, to a muscle of the second limb based on thereal-time measurements of the cardiac cycle of the user associated withthe second limb and the real-time measurements of the musclecontractions of the second limb wherein the second compression sequenceis synchronized to commence when both the local blood flow at the secondlimb is in the diastolic phase and the muscle in the second limb is in anon-contracted state.